Current self-propelled road milling machines generally have a drive motor for propelling the road milling machine and for moving the tools.
For cooling the drive motor and the hydraulic liquid, current road milling machines have a cooling system, which usually consists of a fan for drawing in ambient air, a cooler, and a suction channel. The suction channel, which is usually formed by parts of the chassis, has an intake opening that is directed either to the rear—that is, in the direction counter to the machine's direction of travel—or to the front—that is, in the machine's direction of travel. Accordingly, the ambient air is drawn in either from the rear or the front. The suction channel runs from the intake opening along the longitudinal axis of the road milling machine to a vent opening located directly in front of the cooler. In order to prevent debris, e.g., small particles of milled material or construction waste, from getting into the cooler, a gratelike cooler grill is located in front of the suction channel's intake opening.
The cooler itself has several ducts around which ambient air may circulate. They are located in front of the vent opening, and a coolant for the drive motor is flowing through them. A fan is provided either in front of or behind the cooler, as seen from the direction the air is flowing, in order to draw in the ambient air. In this context the so-called combination coolers should be mentioned in which several separate cooling circuits are provided, e.g., a cooling circuit for the drive motor coolant—as described above—a cooling circuit for hydraulic fluid, and, if necessary, an additional cooling circuit, e.g., for charge air. All of these are configured on the same principle.
Current road milling machines, which have suction channels directed either to the front or the rear, have the disadvantage that despite the cooler grill a great amount of dust and dirt can enter the suction channel and eventually reach the cooler and the fan. Furthermore, it is also disadvantageous that the cooling system described generates a great amount of noise.